Intravenous catheters are well-known medical devices that are used for obtaining blood samples or injecting fluids, such as blood, medication, intravenous liquids, water, and the like, into a patient's bloodstream. Throughout the years, many varieties of intravenous catheters have been developed and used, some having more success than others. Most prior art intravenous catheters require a cutting means, usually a needle, which is used to insert an elongated, hollow tube into the vein of the patient. The needle first penetrates through the skin of the patient and then pierces the vein to allow the hollow catheter tube to be inserted into the vein. After the catheter tube is inserted, the needle is removed leaving only the flexible catheter tube in place. Depending upon the desired use, the catheter tube can remain in the vein for a relatively short period of time or can remain for days or weeks at a time.
One of the more widely used intravenous catheter devices utilizes a hollow needle that has a flexible catheter tube fitted axially on the outside of the needle. The needle penetrates the skin and the wall of the vein creating a small opening for the catheter tube to pass through. However, since the outer diameter of the needle is smaller than the outer diameter of the catheter tube, the catheter tube must be forced into a smaller opening causing considerable pain and discomfort to the patient. Also, it is possible for the vein to become perforated due to the additional force needed to push the catheter tube through the smaller size opening in the vein. As a result, both the needle and the catheter tube can possibly pass entirely through the vein, rather than being inserted into the lumen of the vein. If this occurs, the vein usually becomes collapsed or ripped and cannot be used for intravenous purposes until fully healed. As a result, the catheter tube must be placed in another location in a different vein.
Another popular intravenous catheter device also utilizes a large, hollow needle which has the catheter tube placed axially within the hollow channel formed in the needle. The needle first penetrates the skin and the wall of the vein to place the catheter tube within the vein. Since the needle has a larger outer diameter than the catheter tube, an excessively larger opening is made in the wall of the vein that cannot be fully occupied by the smaller catheter tube once the needle is removed. As a result excess bleeding that can last hours and sometimes days may occur around the opening until the vein can properly heal itself around the tube to prevent further bleeding. The opening could be possibly further enlarged by the movement of the catheter tube during the changing of the dressing surrounding the catheter tube which inhibits the healing process.
A solution to the bleeding problem caused by an over-size or under-size needle is to simply utilize a needle that has the same outer diameter as the catheter tube. However, from a physical standpoint, such a catheter system could not be created using prior art needles and tubing since the insertion needle has always been removed from the vein once the catheter tube has been inserted As a result, a larger or smaller size opening would have to be formed in the patient's vein.
Therefore, there is a need for an intravenous catheter that utilizes a cutting system which creates an opening that is the same size as the outer diameter of the catheter tube. Such an intravenous catheter system would eliminate excess bleeding and should alleviate some pain since the catheter tube would not be forced into a smaller opening in the vein. To be effective, such an intravenous catheter should be easy to insert into a vein and should also be easy to manufacture.
A partial solution to this problem was developed and disclosed in my U.S. Pat. No. 3,584,624 issued June 15, 1971 and now expired. This invention utilized a flexible tubular portion that was affixed to a cutting tip by permanent adhesive. While the structure was effective, one of the major problems encountered in manufacturing this device was the enormous amount of time and effort that was needed to properly glue or adhesively affix the cutting tip to the catheter tube. This problem prevented the device from being mass produced since the bonding of the cutting tip to the tubing is so critical. The cutting tip cannot become unattached from the tubing while in the vein since the tip would enter the bloodstream and cause imminent death to the patient. Therefore, there is a need for an improved structure and method for permanently affixing the cutting tip to the catheter tube which does not require great effort yet achieves a solid and dependable bond.